The U.S. government spends upward of $100 million annually to provide foreign security and law enforcement personnel from developing nations with counterterrorism training but fails to vet them or assure they depart the county upon completion of the course. In some cases, the foreign nationals leave the training program unauthorized and the U.S. doesn’t bother tracking their whereabouts. Since the candidates weren’t properly screened in the first place, there’s no telling the kind of national security threat they could present.

The program is known as Antiterrorism Assistance (ATA) and the U.S. State Department funds it. From fiscal year 2012 to 2017, the agency doled out $715 million to train about 56,000 security force officials from dozens of “partner nations.” Nearly 3,000 of those participants were trained at facilities in the United States with anemic oversight from the government. The goal is to enhance the capability of foreign partners to prevent acts of terrorism, address terrorism incidents and capture and prosecute individuals involved in terrorist acts. The problem is that the program itself is vulnerable from a security standpoint, according to a federal audit released this month. Participant data is inaccurate or incomplete and training facilities are susceptible to breaches and attacks, the probe found.

In fact, what prompted the audit into this decades-old State Department program was the lax security at a Virginia ATA training facility. A south Florida news reporter brought it to the attention of veteran congresswoman Ileana Ros-Lehtinen after filming herself driving into the facility without being stopped or questioned. “And worse, she walked up to an explosives storage area undeterred and undetected,” according to a statement posted on Ros-Lehtinen’s congressional website. Residents near the facility also reported that some of the foreign nationals at the Virginia compound were taking unauthorized departures from the training. Ros-Lehtinen asked the Government Accountability Office (GAO), the investigative arm of Congress, to launch a probe and the findings are distressing.

“Among participants trained in the United States since 2012, ATA has documented 10 participant unauthorized departures from ATA activities and provided related information to the Department of Homeland Security (DHS) for follow-up,” the GAO states. “In addition to these 10, ATA recently identified 20 ATA participants trained in fiscal years 2012 through 2016 for whom departure from the United States following the completion of training is unconfirmed.” Officials running the ATA program admitted to congressional investigators that there is no formal process to confirm participants’ return to their home countries following the completion of training. “Without such a process, ATA may not be able to assess the extent to which it is using training in line with program goals,” the report says. “Further, State may not be able to provide information to DHS about participants whose failure to depart may warrant enforcement action.”

Ros-Lehtinen, who serves on the House Foreign Affairs Committee, says ATA’s inaccurate or incomplete participant data is troubling because the U.S. can’t assure individuals were fully and properly vetted and program’s success—or failures—can’t be measured. The congresswoman is especially bothered by the unauthorized departure from ATA programs and participants that DHS had no indication departed from the U.S. “So, who are these people, where did they go, and why is there such a gap in communication between ATA and DHS?” Ros-Lehtinen asks. “There was no formal process of actually following up and ensuring that these participants actually got on a plane and returned home. This might be a small number of participants, but given what we know, I suspect that if a deeper dive was done we might find more unauthorized departures.”

Since its inception in 1983, ATA has trained and assisted over 84,000 foreign security and law enforcement officials from 154 countries, according to State Department figures. Most of the recipients are poor nations that lack resources to keep an effective antiterrorism program and infrastructure, according to the agency. Training includes bomb detection, crime scene investigations, airport and building security, maritime security, dignitary protection, and numerous other disciplines to increase their counterterrorism capabilities and capacity. “These officials are now better prepared to fight terrorism and protect Americans overseas in times of crisis,” the State Department claims.